1. Technical Field
The present invention relates to a wiring board and a mount structure in which the wiring board is mounted on a mounting object such as an electrooptic panel, for use in personal computers, portable phones, etc. and to a method for manufacturing the mount structure including the step of connecting the terminal groups formed on the components.
2. Related Art
Known electrooptic devices mounted to electronic devices such as portable phones, notebook computers, and TV sets include a structure having an electrooptic panel and a wiring board mounted on the electrooptic panel. When a driving circuit for driving the electrooptic panel is mounted to the panel, the wiring board supplies display data and control signals sent from the display control system of the electronic device to the electrooptic panel. When the driving circuit is not disposed on the electrooptic panel, the driving circuit is mounted on the wiring board or another circuit board connected to the wiring board. In this case, the wiring board supplies the driving signals output from the driving circuit to the electrooptic panel.
With the above structure, a plurality of input terminals is arrayed in line along a rim of the electrooptic panel, while a plurality of connecting terminals is arranged in line along a rim of the wiring board in correspondence with the input terminals. When the wiring board is mounted to the electrooptic panel, the input terminals and the connecting terminals are opposed to each other with an anisotropic conducting material in between, to which heat and pressure are applied by tools so that corresponding input terminals and connecting terminals are electrically connected. For the anisotropic conducting material, insulating resin containing dispersed conductive particles is used so that the input terminals and the connecting terminals are electrically connected via the conductive particles.
The connecting terminal array of the wiring board is disposed in proper correspondence with the input terminal array of the electrooptic panel. However, the wiring board expands or contracts significantly because it is basically made of polyimide resin, which changes the pitch of the connecting terminal array. This causes a pitch gap between the connecting terminal array and the input terminal array formed on the glass substrate that is hardly influenced by temperature changes or moisture absorption. This causes disagreement of the positions of the connecting terminal array and the input terminal array, thus posing the problem of mount failure.
Therefore, a mount structure is proposed in which the input terminals and the connecting terminals are disposed in belt shape along a plurality of lines that passes through a common point (a phantom center point) that is apart from the input terminal array and the connecting terminal array in a predetermined direction intersecting the direction of the terminal arrays, so that even if the pitch of the connecting terminal array changes to some extent because of the expansion or contraction of the wiring board, the pitches can be agreed by relatively shifting the input terminal array and the connecting terminal array in the direction in which the distance from the common point changes (for example, refer to JP-A-2003-258027).
Known methods for mounting the wiring board on the electrooptic panel in such a mount structure includes a method for aligning the electrooptic panel and the wiring board using a reference mark formed at one of the electrooptic panel and the wiring board and a scale formed at the other (for example, refer to JP-A-2003-258396).
However, the alignment method using the reference mark and the scale requires the operator to determine the amount of the expansion or contraction of the wiring board, thus posing the problem of complicated work. Moreover, since the scale is constructed of a plurality of linear patterns, extremely thin linear patterns are needed for higher alignment accuracy. Particularly, a wiring board made of polyimide or the like has the problem of low yields and high manufacturing cost because of difficulty in increasing the accuracy of the pattern of the alignment mark. This method also has the problem of low visibility and taking much time and labor for alignment work because of a large number of linear patterns formed on the scale.